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This invention relates generally to Laser Diodes and more particularly to Pump Laser Diodes offering improved wavelength stability through use of Fabry-Perot cavity and Fiber Bragg Gratings.
Laser diodes, which are used as pumps at an operating wavelength of approximately 980 nm in erbium-doped fiber amplifiers, are stabilized around this wavelength for efficient pumping. However, the emission wavelength of the laser with a conventional Fabry-Perot cavity formed by laser facets tends to change with the temperature of the laser. The temperature change can be environmental and/or induced by the Joule heating of the diode at increased forward currents.
According to a first aspect of the present invention, there is provided a pump laser diode for providing improved stability at higher operating temperatures. The pump laser diode includes a Fabry-Perot cavity formed by laser facets and Fiber Bragg Gratings (FBG) in a pump module, wherein facet optical mirror losses are made to increase for wavelengths longer than the required emission wavelength, thus permitting the diode to be locked to the emission wavelength while operating at higher temperatures.
In a further aspect of the invention, a stack of materials with different refractive indices is deposited on the back facet of the laser diode.
Another aspect of the present invention provides a method for providing improved stability at higher operating temperatures for a pump laser diode. The method includes providing light from a pump module into a Fabry Perot cavity having mirror optical losses, and increasing the mirror optical losses of the cavity at a wavelength that is not the emission wavelength.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.